I recommend the head soak first. After you've done a few strong cleanings, if there's still no or little flow, take some lint free cloths or coffee filters (cloths preferred), soak them in cleaning solution and set them in the capping station. Park the heads of the cloths and let it soak for 60 mins. Afterwards, try another strong clean, then a nozzle check. If still a problem, the soak one more time. Outside of that, the heads might need to be replaced, but typically a good head soak with unclog the nozzles in my experience. I'm sure others have insight too. Good luck!